Weapon Name- M12
Round Type- 6.5mm Grendel
Over-all length- 30 inches, 24 inches
Barrel length- 22 inches, 16 inches
Weight- 6.5 lb, 6.2 lb
Rate of Fire- 600 RPM
Feed Mechanism- Detachable Box Magazine
Round Capacity- 42, 60
Effective Range- 600 meters
Range- 1000 meters
Accuracy- 1 MOA
Accessories- Picatinny Rails
Quick switch firing mechanism- N/A, Extra Trigger
Scope/Sights- Picatinny Rails, 4x Thermal Scope
Muzzle Velocity- 820 m/s, 8 grams
Firing System- Short Stroke Gas Piston
Miscellaneous/electronic information- The weapon is essentially a bullpup XM8 chambered in 6.5mm Grendel caseless rounds.
Basic Information
The weapon is essentially an enlarged bullpup XM8 firing the 6.5mm Grendel round. Based on the firing system, it combines aspects of the LSAT with the XM8, to allow the weapon to possess the capability to realistically fire caseless ammunition, primarily the seal on the bolt which seals the round in the chamber. The XM8 uses an extremely reliable short stroke gas piston, which is substantially more reliable than direct impingement systems, while still possessing the same level of accuracy and low recoil. Compared to long stroke gas pistons, the weapon has a lighter bolt and piston mass and a shorter action, which reduces the recoil significantly, while still retaining much of the high reliability and durability. Key differences with the original XM8 are ambidextrous controls, a quick adjustable right or left ejection port, a slightly shorter folding stock compatible with AR-15 furniture, being STANAG compatible, and a higher degree of modularity. While the original XM8 was designed to work with form fitting pieces to increase their cohesion with accessories and the weapon, to provide greater ergonomics and reduced weight, it lacked standard modularity available from equipment such as picatinny rails. This firearm possesses the option for the same close fitting accessories, however it also possesses optional picatinny rail attachments, with keyhole mounting, that allows the picatinny rails to mounted to the firearm. This opens up the weapon to being able to use a variety of different weapon attachments, such as lasers or scopes. It possess a lower profile top rail, instead of the raised rail found in the traditional XM8, as well as a non-reciprocating, fixed non-folding charging handle. The slimmer profile as well as changed accessories makes the weapon lighter, or approximately 1 pound lighter than a standard XM8.
The weapon is essentially patterned off of the XM8, however it utilizes the 6.5mm Grendel caseless round, which causes the weapon to be much larger. The short stroke gas piston is considered to be more reliable than direct impingement systems while retaining the same low recoil and high accuracy, and in general is more smoothly operating than long strike gas pistons (less recoil, muzzle rise, and higher accuracy). The firing system is based off of the XM8 which uses a short stroke gas piston system, similar to that in the AR-18, FN SCAR, or XM8 In July 2007, the US Army announced a limited competition between the M4 carbine, FN SCAR, HK416, XCR, and the previously-shelved HK XM8. Ten examples of each of the four competitors were involved. Each weapon fired 60,000 rounds in an "extreme dust environment." The purpose of the shoot-off was for assessing future needs, not to select a replacement for the M4. The XM8 scored the best, with only 127 stoppages in 60,000 total rounds, the FN SCAR Light had 226 stoppages, while the HK416 had 233 stoppages. The M4 carbine scored "significantly worse" than the rest of the field with 882 stoppages. However, with the HK416, 117 of the 233 malfunctions were from just one of the 10 weapons. Over-all this gives the weapon between 4-8 times higher reliability than the M4 carbine or similar firearms, with a variety of operating conditions being less hazardous to the over-all functioning of the firearm, including sandy or wet condition. The weapon also has substantially higher heat tolerance than most firearms, even higher than most similiar firearms. While an M16 is only expected to be able to realistically fire 15-20 rounds a minute, the XM8 can fire over 80 rounds per minute with relatively little difficulty, which is roughly equal to the firing rate of the M249 machine gun, and twice that of the M27 IAR at 36. Heckler and Koch engineers fired 4 high-capacity magazines, with 100 rounds apiece, in less than 5 minutes from their XM8 entrant, or 400 rounds in less than 5 minutes.
The weapon uses a detachable polygonal cobalt chrome "flow formed" 6 groove 1:9 inch (1 complete turn in 1 in 9 / 228.6mm) right hand turn barrel; the barrel is made of an alloy that contains more than 50 percent cobalt. The barrel is roughly 13% heavier than standard steel barrels, but is more erosion and corrosion-resistant and is designed to retain high strength during long-term exposure to high temperatures. Cobalt alloys are frequently used in the aerospace industry, such as the hot-gas section of turbine engines. A proof of concept M240 7.62mm x 51mm NATO barrel, in practice, had 24,000 rounds test-fired through it, causing it to reach temperatures of 1,100 degrees, without failure. A steel barrel would have failed under such treatment. The barrel itself, combined with polygonal rifling, is extremely durable, and has a minimum 20,000 round barrel life, although it is possible to extend this or get use out of the rifle after the minimum is reached. The barrels come in 10, 14.5, and 20 inches.
Utilizing the 6.5mm grendel cartridge, it is much more accurate and powerful than the standard 5.56mm, with an effective range of approximately 600 meters, and a maximum effective range of around 1200 meters; the round is inherently accurate, and standard factory ammunition possesses around Sub 1 MOA, with .3 MOA not being uncommon with match grade ammunition. Possessing around 2600 joules, accelerating a 7.8 gram cartridge nearly 820 m/s (100 m/s more than an Ak-47 cartridge) and compatible with virtually any 5.56mm or .223 Remington weapon, it's accuracy and firepower greatly extends the capabilities of any standard NATO weapon, while still maintaining the compact size and light weight of those systems. Although the cartridge is called the 6.5mm Grendel, it is actually 6.7mm in diameter, and is frequently reffered to by the 6.8mm desgination. It's inherent accuraccy, high ballistic coefficient and naturally high power makes it a barrier shattering cartridge, capable of fullfilling roles similiar to both smaller intermediate cartridges such as the 7.62mm x 39mm, and the 5.56mm, while also performing functions of the 7.62mm x 51mm NATO. With a ballistic coefficient of .51, it has more energy than a .308 at 600 yards, despite having less at the muzzle. Compared to the 5.56mm, it has 45% more energy at the muzzle, and nearly tripple at 600 yards, as well as a flatter trajectory, drastically increasing it's effective range. It's range is nearly identical to the .308, making training fairly similiar between both cartridges.
The weapon utilizes a 100 round spring assisted rotary magazine, which spins the rotary mechanism with each backwards cycle of the bolt. This is designed to provide additional energy in to pushing forward the follower, clicking the magazine forward, which in turn helps to spin the magazine. Instead of being entirely dependent on the spring of the magazine, which is consequently heavier and less reliable as it enlarges, instead the magazine has an additional device which helps to push the floor plate forwards. The magazine is designed much more like snail drum magazine in construction, and forms a circle around a single axis, however this fits inside the bullpup weapon.
Each barrel possess a muzzle break designed after the surefire muzzlebreak. Though there are numerous ways to measure the energy of a recoil impulse, in general a 10% to 50% reduction can be measured. Besides reducing felt recoil, one of the primary advantages of a muzzle brake is the reduction of muzzle rise. This lets a shooter realign a weapon's sights more quickly. This is relevant for fully automatic weapons. The weapon also possess a hydraulic recoil buffer similiar to that in the M249. The Hydrualic recoil buffer extends all the way back in to the stock, The design of the weapon and it's straight back recoil impulse, as well as the tighter, more steady grip on the weapon, combined with the impact gel recoil pad, makes the weapon very easy to use and relatively comfortable. The weapon uses a Blackbox round counter that can be hooked up to an LCD screen to show the rounds remaining. The magazines are generally color coded, which provides indication of how many rounds are within each magazine, although loading in another magazine that does not meet the criteria can result inaccurate round counting predictions; the round counter mechanism itself, however, will not falter. The weapon is made from composites and polymers similar to the P90 and XM8, to both reduce the cost and weight as of the weapon, as well increase the durability. The weapon fires from a closed bolt for both maximum accuracy and reliability. The weapon has picatinny rails, and thus an array of different sights are available for the weapon.
